1. Field of the Invention
The present invention relates to a method and apparatus for testing bump electrodes of semiconductors and, more particularly, to a method and apparatus for testing pull or tensile strength of the same.
2. Related Art
The high density packaging or mounting of electronic circuit elements has been demanded to reduce manufacturing costs of computers, hybrid integrated circuits (ICs) for automotive electronic devices. The flip chip packaging method using semiconductor bump electrodes (bump electrodes) requires less junction areas than other packaging methods and provides higher junction strength. Therefore, it became more attractive as the high density packaging method. From the trend that products are required to be highly integrated type and have multiple functions in recent years, the ICs must be also highly integrated and, hence, the bump electrodes must be finely formed.
It is known as the pull strength or tensile strength testing of those bump electrodes that, as shown in FIG. 5, after forming bump electrodes 21 of a semiconductor chip 20 on a substrate 40, the semiconductor chip 20 is pulled in its entirety by a pulling jig 30 to test the pull strength of the bump electrodes 21. It is also known as disclosed in JP-A-57-2550 that wire leads are connected to bump electrodes and thereafter pulled to test the pull strength of the bump electrodes.
However, in the method of pulling the semiconductor chip 20 to detect the pull strength of the bump electrodes 21 after forming the bump electrodes 21 of the semiconductor chip 20 on the substrate 40 as shown in FIG. 5, the semiconductor chip 20 is pulled in its entirety for the testing. Since the bump electrodes 21 may have different pull strengths, even in the case that only one of the bump electrodes 21 of the semiconductor chip 20 has low strength, it cannot be determined which one has the low strength. It cannot be measured either how low the strength of such one bump electrode 21 of the low strength is. Further, in the method of pulling the wire leads connected to the bump electrodes, it has a problem that, if an adhesive such as the one in the cyanoacrylate system or the like is used to connect the wire leads and the bump electrodes, breakage is likely to occur at the boundary face between the adhesive and the bump electrodes before the breakage of the bump electrodes. It also has a problem that, if the adhesive in the epoxy system is used, the adhesive takes several days to provide its maximum junction strength and is not practical for the testing in a short period of time.